DELIVERABLE Recommendations of best practices in diagnostic and discharge D Version 1

Transcription

1 DELIVERABLE Recommendations of best practices in diagnostic and discharge D Version 1 Project number: FP GC-ELECTROCHEMICAL-STORAGE Duration of the project: 36 months Project Co-ordinator: Renault Work Package and Task: WP6, Task 6.2. Main Author: Elise SENECHAL (EDI) Contributors: Benoît BATTISTELLA (EDI), Richard LAUCOURNET (CEA), Marcus DÖRR (Fraunhofer), Gilles GARIN (SNAM), Jérôme PEYRARD (Renault). Nature: Report Dissemination level: PU Due delivery date: M20 Actual delivery date: M20 Abstract Nowadays, forecast sales figures for (hybrid) electric vehicles are promising. The batteries in those vehicles which are specific Lithium-Ion batteries need to be properly recycled at their end of life. Today the existing recycling processes are either a treatment by hydrometallurgical or by pyrometallurgical way. Nevertheless when a battery is recycled several measures need to be taken. Indeed, there are risks caused by high voltage and current of the battery. So, these measures consist in a diagnostic of the state of charge of the end of life batteries followed by a fitted discharge. This first step aim making safety the battery for the following steps which are the dismantling and the recycling process. Two main methods of electric discharge may be used according to the state of battery : resistive discharge or electrolytic discharge.

2 Contents 1. Summary 1.1. General objectives This report is dedicated to propose some recommendations of best practices which are required for the diagnostic and the discharge of batteries in terms of safety for operator and environmental impact Introduction & methodology Besides their weight and size, the electric vehicles batteries involve some risks linked not only to high voltage and current (as previously said) but also to the toxic elements of the cells. That is the reason why some recommendations are given in this report in order to alert the future operators to these risks. A protocol of diagnostic of batteries will be proposed in the first part of this report. Then two methods of discharge of batteries will be described. The methodology used was to test different methods of discharge with our historical understanding in this field thanks to our activity and with the requirements given by Europeans standards. Thus the information gained during this work allowed to get the best practices for the diagnostic and the discharge and to realize a protocol to make safety the batteries for the dismantling and the recycling process Starting point: state of the art & reference documentation This report was written from basic knowledge and skills of EDI in recycling of Li-ion batteries in general. Regarding electrical risks EDI is related to the regulations and to our electrician skills. The recommendations are given from findings and real results obtained during several tests on EDI site Description of the work EDI realized several tests of diagnostic and discharge of batteries thanks to inputs and indications providing by Renault

3 1.5. Reference to intermediate reports and/or other deliverables Some findings and recommendations are given in the interim report M18. The recommendation about relaxation phenomena is explained in Deliverable D Version Description of the results The main results on this subject are described in part 5 of this report

4 2. Report ABSTRACT... 1 CONTENTS INTRODUCTION DIAGNOSTIC OF BATTERIES METHODS OF DISCHARGE ELECTRIC DISCHARGE ELECTROLYTIC DISCHARGE GENERAL RECOMMENDATIONS CONCLUSIONS Introduction The diagnostic of the battery (What is the state of charge?, Is it a damaged battery?...) is important to decide the method of discharge. Euro Dieuze Industrie (EDI) did not study the discharge to reuse the battery but to recycle it. So, we studied the complete discharge (until around 0 V) in order to avoid electric risks for operator during the dismantling. RENAULT gave inputs on different battery pack constructions and some indications for different cases (classic EoL, crashed, ) in order to propose a list of best practices 2. Diagnostic of batteries Renault sent some batteries from different cases: - Classic end of life batteries (EoL) - Damaged or defective batteries At battery reception a global checking of the state of the battery (voltage and visual control) must be done in order to define if we are forced to discharge. Some batteries have been received without indications from the constructor, so it is really important that recyclers have their own checking system, especially for the voltage. Even if we recommend indicating the voltage and the source of wasting (EoL, accident, test ) to the constructors when they send their batteries (for example to create a labelling on the packaging with this information). Nevertheless as the FMEA analysis points out, some mistakes are possible and some indications can be wrong. So despite the presence of indications from the constructor, this checking at the battery reception will be always done by the recycler for more safety

5 However, a battery of electric vehicle cannot deliver current if it is out of vehicle. So EDI developed a system allowing to plug in the battery and to generate a current of 12V and thus to simulate the current send by the lead battery in the vehicle. This 12 V current intend for closing the relays in the battery. One other safety measure named plug system has been designed by constructors for safety reasons. This plug system is particularly intended for firefighters in accident case: the firefighters unplug the system after an accident in order to cut the battery power and to avoid a fire. After the connection at the plug system and the 12V system, the voltage can be measured at battery terminals. In case of damaged battery, any risks is taken and the battery will be put in a fitted discharge (electrolytic discharge to see hereinafter) without diagnostic. Procedure: 1. To put the safety equipment 2. To connect the plug system 3. To connect the 12V power (safety relays) 4. To check the voltage 5. Diagnostic to determine the discharge method The diagnostic consist in measuring the voltage of battery and determining the necessity or no to discharge it. Depending of value of the tension, the battery will be discharged - 5 -

6 either by resistive electric discharge or by electrolytic discharge way or the battery will not be discharged: If the value of tension equals exactly 0V the battery is discharged by electrolytic way, like a damaged battery because we consider that the voltage of battery even totally discharged never indicates exactly 0V but some millivolts. So, we consider that a battery which indicates exactly 0V is suspect. Maybe some connectors are broken. If the value of tension is superior at 0V and inferior at 60V the battery don t need a discharge because the battery is in very low tension. In French regulations, the very low tension is the range of electric tensions which cannot involve a hazardous current in human body (NF C ). So, the battery can go directly to the dismantling step. If the value of tension is superior at 60V the battery is discharged by electric resistive way. Following, the protocol for the diagnostic of batteries is illustrated

7 . Battery reception Labelling Comment : (e.g.: Source of wasting) Labelling and visual checking SOC : % or Tension: V Visual checking Defective or damaged battery - Solvent leak? - Visual damages (cracked dented, burned battery ) U Battery = 0V Electrolytic discharge Diagnostic of SOC 0V < U Battery < 60V Dismantling U Battery > 60V Electric discharge Figure 1 : Protocol for the diagnostic of batteries The tension can reach 400V CC so, it is necessary to use specific safety equipment and to train the operator in electrical risks. The list of safety equipment is detailed in part

8 3. Methods of discharge Euro Dieuze Industrie has developed two methods of discharge: - Electric discharge by thermal diffusion through resistances - Electrolytic discharge thanks to electrochemical solution 3.1. Electric discharge Electric discharge would be preferred for classic EoL for several reasons: - Time: the electric discharge is less long than electrolytic discharge. - Safety: The electrolytic discharge needs opening of the full battery (contrary the electric discharge) because it is waterproof. In the future, battery conception should have a specific system which permits to enter the electrolytic solution in the battery. - Cost and space: The electrolytic discharge needs a reagent (electrochemical solution) which would be stored and managed. Moreover, the electrolytic vats will take up a huge area V Tension display Electrical cabinet R Resistor Plug system EV Battery + - Relay 12 V supplying Figure 2 : Drawing of electric discharge - 8 -

9 Procedure: 1. To put the safety equipment 2. To connect the plug system To supply relay in 12V To check the voltage If U > 60 V 3. To connect the resistor to the battery terminals. 4. To discharge the battery through the resistor until the voltage is < 1V The battery is discharged And safe for the operator handlings Depending of kind of battery a specific protocol must be developed to identify the connectors which must be controlled for the diagnosis. This task must be done in collaboration between the recycler and the constructor. An important discharge current may lead to a high increase of the temperature in the battery which would destroy the cells. After discharging, it is possible to observe a relaxation phenomenon (the currant reincreases after the discharge during time. That is the reason why we recommend to discharge the battery down to a very low voltage (EDI : < 1V) and to avoid waiting - 9 -

10 between discharging and dismantling. The time of electric discharge can vary from some hours to one day but more the discharging is fast more the relaxation phenomenon is important Electrolytic discharge Electrolytic discharge would be chosen for crashed battery in order to avoid fire risks during the electric discharge (for example caused by a short circuit). We have tested different solutions, at different concentrations in order to compare it about some criteria: - Stability of batteries metals in the electrolytic solution during the discharging. - Efficiency of solution (discharging time, minimum voltage ). - Chemical classification and toxicity of the solution for logistic and safety reasons. - Re-use solution for some discharging. Procedure: 1. To analyze the electrolytic solutions (initial state) : conductivity, ph, temperature, P,F, COT 3. To submerge the battery in the electrolytic solution 4. To go out the battery after 24 hours The battery is discharged And safe for the operator handlings 5. To analyze the electrolytic solutions (final state): conductivity, ph, temperature, P,F, COT

11 The aim of the analysis of electrolytic solution is to check that there are not electrolytic leaks (result from cells solvent) during the discharge and to follow the potential metals presence in the solution. The temperature allows ensuring that the reaction is not too exothermic. Extractor hood Electrolytic solution Gas emission EV Battery + Figure 3 : Drawing of electrolytic discharge During an electrolytic discharge, we can observe a gas emission resulting from the water electrolysis and maybe from reactions between the different materials of the batteries and the electrochemical solution. So, it will be probably necessary to intend a recovery and a treatment of this gas. Moreover, the electrolytic solution will need regeneration or disposal process. The picture below illustrates this gas emission. Figure 4: Illustration of gas emission during the electrolytic discharge

12 The kind of tested electrolytic solutions was saline solutions and solutions of sodium hydroxide at different concentrations. Some solutions seem suitable whereas some solutions showed a strong reactivity with materials of batteries, particularly the solution of sodium hydroxide which reacts strongly with the aluminum. This can be explained by the following reaction: 2 Al + 2 NaOH + 6 H 2 O 2(Na 2 Al(OH) 4 ) + 3 H 2 This reaction and the electrolysis of water during the discharge lead that the gas emission mainly corresponds with hydrogen (H 2 ). But the hydrogen at high concentration in presence of water represents a strong danger. Therefore, it would be more careful that electrolytic discharge is realized by experienced factories with skills in chemistry and risks prevention. Today, it is difficult to discharge a battery by this method because the battery is waterproof and opening charged battery is hazardous. Therefore, we may plan an opening system of the battery at the full battery conception level such as an outlet plug in order to break the impermeability. That is the reason why EDI started electrolytic discharge tests at module scale and then after more knowledge on this subject at full battery scale. 4. General recommendations The storage of EV batteries before the diagnostic and the discharge must be done in specific space equipped of fire alarm with dousing system. For the discharging area, fire protection system are recommended, like fire extinguishers. For the diagnostic and the discharge steps, the safety equipment and the electrical authorizations were defined for the operators: Authorization B2V (in French regulations) Using of insulated tools in accordance with NF EN Using of face mask (NF EN 166 et 170) Using of insulated gloves (NF EN 60903) : the class 00 is enough Insulation of ground (NF EN 61111) : the class 0 is enough Facemask Gloves: Type 00 (efficient until 750V) Insulating mat: Type 0 (efficient until 1500V)

13 The gloves and mats would be checked before each using and also yearly by a qualified person for the insulating mat. As illustrated here below, at least the discharging area must be delimited: Chain or red and white strip Signalisation Works area We recommended a wire-mesh area where only qualified persons are allowed to enter

14 5. Conclusions In this report, the recommendations of best practices to make safe the battery for operators during the dismantling are detailed. To put in safety the battery consists in diagnosing the state of charge of the battery and discharging it. However, these two steps involve electrical risks which must be known and controlled by recyclers. A protocol of diagnostic of batteries was defined by EDI and is given in this report. This protocol allows to guiding the battery to the best discharge method (in terms of safety for operators) and also avoiding waste of time for already discharged batteries. Regarding the discharge, EDI developed two methods. A first method for classic end of life batteries operates by resistive way. This first method is simple and quick if there are good connectors for each kind of battery design and does not need the opening of full battery. Maybe an universal connector would be interesting to develop between the manufacturers. However, the voltage of the battery can reach 400V (in continuous current) that is the reason why the safety equipment wearing is recommended and the training of operators in electrical risks is necessary, particularly because of the relaxation phenomena. Nevertheless, the discharge of damaged battery by resistive way can involve risks such as a generation of fire caused by a short circuit. Moreover, EDI recommends to not measuring the voltage of damaged batteries because we do not know the state of battery inside the casing. To avoid this risk, EDI developed a second method of discharge by electrolytic way which consists in submerging the charged battery in an electrochemical solution. The disadvantage of this second method is the fact that a gas emission is observed during the discharge and so it must be extracted and treated. To conclude, it is important to be aware of risks that involve EV batteries. The high voltage of batteries and the reactivity of some electrolytic solutions represent important risks. Qualified persons with skills in this field are needed in order to set up a diagnostic and discharge workshop. In the future, EDI will highlight the disadvantages of batteries design for these steps of diagnostic and discharge in the task 6.5. such as the absence of an opening for electrolyte feeding inside the battery and the wide range of connectors

15 3. Implementation on other WP No implementation on other WP 4. References Préparation à l habilitation des NON électriciens, EL:B080-EL:B081,apave. Carnet de Prescriptions de sécurité d ordre électrique, apave, édition avril Guide des équipements de protection individuelle dans le cadre des opérations électriques, 2011, CATU